It’s just over a week after Rihanna announced herinitial summer 2011 tour plans, and now the pop-R&B starlet has expanded not only the tour’s...

It’s just over a week after Rihanna announced herinitial summer 2011 tour plans, and now the pop-R&B starlet has expanded not only the tour’s calendar, but also its billing.

Grammy Award-winning musician Cee Lo Green, whose most recent work includes the ubiquitous single “F**k You,” will appear on each night of the upcoming Loud Tour as a special guest. Also confirmed are 10 more concerts on their shared itinerary.

New dates include a block of six Canadian concerts to follow a previously announced June 7 show in Toronto. The fresh string of shows begins June 10 at the Bell Centre in Montreal, QC, and continues through June 24 at Rogers Arena in Vancouver, BC.

The Loud Tour will also make additional stops in the United States on July 4 at Hard Rock Casino in Albuquerque, NM; July 8 at American Airlines Center in Dallas, TX; July 9 at Toyota Center in Houston, TX; and July 24 at TD Garden in Boston, MA.

Tickets are already available for the seven previously announced concerts; public ticket sales for the newer concerts will open over February 18, 19 and 21. As with the earlier onsales, ticket prices are largely in the range of $20 to $120, according to updated Ticketmaster.com listings.

In the statement announcing her new Loud Tour companion, Rihanna commented, “I’m a huge fan of Cee Lo since his days with Goodie Mob and with Gnarls Barkley. He’s a musical genius, continually reinventing himself and I’m thrilled to have him join me on tour.”

Green said that he considers it “an honor and a blessing to be able to go out with a talent such as [Rihanna],” also adding, “I look forward to doing my part to make the tour unforgettable for the fans that come out and see us.”

The recent addition of Green — and the varied demographic of his fan base — could be a boon for Rihanna and her 2011 tour. The Barbadian singer’s Last Girl on Earth Tour with Ke$ha last summer was dogged by lower-than-expected consumer interest and slow sales, resulting in multiple concert cancellations and venue down-grades.

Rihanna – Loud Tour itinerary:
(Dates are subject to change.)

June 4 Baltimore, MD 1st Mariner Arena
June 7 Toronto, ON Air Canada Centre
June 10 Montreal, QC Bell Centre
June 18 Winnipeg, MB MTS Centre
June 19 Saskatoon, SK Credit Union Centre
June 21 Calgary, AB Scotiabank Saddledome
June 22 Edmonton, AB Rexall Place
June 24 Vancouver, BC Rogers Arena
June 28 Los Angeles, CA Staples Center
June 30 Oakland, CA Oracle Arena
July 4 Albuquerque, NM Hard Rock Casino
July 8 Dallas, TX American Airlines Center
July 9 Houston, TX Toyota Center
July 19 Uniondale, NY Nassau Veterans Memorial Coliseum
July 21 East Rutherford, NJ IZOD Center
July 23 Philadelphia, PA Wells Fargo Center
July 24 Boston, MA TD Garden